One good thing you might want to mention is the usefulness of grammars. Modules like Parse::Recdescent are enormously useful for parsing highly complex data. You could even talk about them in contrast to "The Burrito Principle" (which is the greatest buzzword ever!), since grammars are usually written from a top-down approach. However, even with grammars, you could still apply the Burrito Principle: it is usually best to work on the most complicated/important subrule within a set of subrules first, as others in the set will usually follow easily.

Update: Cleared up my thoughts.